Abstract:The ophiolite zone in Sanmen area of Longsheng district, Guangxi is tec- topically located at the south-west terminal of the Jiangnan Geoanticline. The stratigraphic sequence in the area includes Hetong Formation and Gong- dong Formation of Upper Banxi Group of Pre-Sinian System, and also Sinian and Cambrian Systems. The spilites occur in the upper member of Hetong Formation. Some deep sea silicolites, shales, and a minor amount of carbonatites are involved in the spilites. In the area where spilites are distributed, there are a large amounts of diabases, and a minor amounts of basic-ultrabasic and ultrabasic complexes. The variation diagram of the chemical compositions of the volcanic rocks- (Fe0)/Mg0 to Si02 indicates that the volcanic rocks in this area are of talc-alkali series (CA) and tholeiite series (TH)，thus the ophiolites belong to the I type which was divided by A. Miyashiro. In the Ti-Zr variation dia- gram, the dots marking the compositions of the volcanic rocks also lie in the field of island arcs. Furthermore, the contents of trace elements in the volcan- ic rocks are very similar to the TH series and the CA series of the island arcs. It is suggested that the ophiolites in this area were formed in ancient island arc environments.
Abstract:The granites of south China are divided into three types on the basis of the geological Characteristics, evolutional law, minerlization process, material sources and genetic mode which has been revealed by them, and combining with the data of stable isotope in present. They are;1) upper mantle differentiataion type; 2 ) continental crustal anamelting-remelting type; 3 ) continental metasomatic type. An overwhelming majority of the Mesozoic granites in South China is related to rare elementes and nonferous metals belonging to the continental crustal anamelting-remelting type. As the depth of sources, the degree of remelting, the composition of original material, the emplacement mechanism are difference. They can be subdivided into three evolution series, 1) Nanling evolution series] 2) Yangzi evolution series] 3) Minyue evolution series. Each of the three series has its properties. It is incomplete that if we shuld not consider the magmatic evolution law when we make a classification of granitoid in South China.
Abstract:Darongshan granitic body occuring as an elongated batholith is composed of cordierite-biotite granite and monzonitic granite, commonly containing dark enclaves, cordierites, sillimanites and garnets, etc. Most of them are the unmelted restites during the formation of magma and only a part of cordierites crys- tallized from magma at depth. The granites crystallized from magma at temper- ature about 680-710℃ under pressure 2-3 Kb and characterized by lower fo2. These show that the granites are the mezo-abyssal intrusions. The magma which make up the Darongshan body is rich in Al and poor in Na and its degree of water suturation is lower than that in common granite. It formed possibly in anatexis of metamorphic sediments riched in A1 and Si (high-grade amphibolite facies).According to the compositions of the unmelted restites auther infers that the magma was produced under pres- surs about 4-6 Kb at temperature 680-730℃. Dungwu movement gave rise to the formation of orogentic belts and made a favourable condition for the anatexis. Later the fault movement brought about the formation of magma and resulted it in an emplacement from late Permian to early Triassic period.
Abstract:The main points of view in this paper are as follows: 1) The assemblages of granites represent the granitic evolutionary sequences if they are located in the common geological element and associated with the closed genetic relation and the order of their formation are determined definitely enough. 2) The Mesozoic granites from Zhuguangshan Batholith represent an ex- ample of biotite-two-mica/muscovite granitic type of evolutionary sequence. They can be divided into three evolutionary cycles and six intrusive stages. The beginning member of each cycle is composed of coarse-grained or medium- grained biotite granitic rocks and the end inember-fine-or medium-grained two mica/muscovite granitic rocks. The geological and petrochemical data in- dicate that this type of evolutionary processes depend on the fH,o and fo2 conditions. 3) Investigation on the granitic evolutionary sequence is an important work and the various ore deposits are related to the different types of evolutions.
Abstract:A brief historical review on the genesis of granitoid has been given and a preliminary genetic classification has been proposed on the basis of the genesis of Jiangxi granitoids. According to this classification, the granitoid has three groups,(1) crustal type granites formed by remelting of the sial; (2) transitional type granites foamed by mixed-melting of the upper mantle or the sima with the lower crust; and (3) mantle type granites derived from differentiation or contamination of basaltic magmas. Each type is further subdivided into several sub-types.
Abstract:The optical sign and birefringence of a cyclosilicate mineral are not only depended on the kinds of the ring of Si-O tetrahedrons and their orientations, but also on the crystallochemical sites of cations. These cations in cyclosi- licates may be classified into several types such as the large cations of "Mica- type", the octahedron cations of "Benitoite-type", the tetrahedron cations of "Beryl-type", the chain-type octahedron cations, the layer octahedron rations of "Sandwich-type" and so on. The one-dimentionality factor always co-exists with the two-dimentionality factor in a crystal structure. On condition that the one-dimentionality factor overpowers the two-dimentionality factor, the crystal has a positive birefringence, conversely, on condition that the two-dimentionality factor overpowers the one- dimentionality, the crystal has a negative birefringence. In the cyclosilicates the structure elements of Si-O tetrahedron ring are a two-dimentionality factor. The ca.tions of "Mica-type" and "Chain-type" are always a factor of one-dimentionality resulting in a positive birefringence, on the contrary, the rations of "Benitoite type" and "Sandwich type" are always a factor of two-dimentionality resulting in a negative birefringence. The cyclo- silicates with tetrahedrons of "Beryl-type" have a structure of three-dimentional framework, and have very low birefringence.
Abstract:Diopside-acmite is a pair of coexistent minerals in a solid solution which dissolves imperfectly. Sometimes they are associated with each other in meta- somatic rocks. But under what physico-chemical conditions can this pair of minerals actually occur togetherp Author has summarized the experimental data on the diopside-acmite paragenesis obtained from the modeling of the forma- tion of the Makeng iron deposit, which is undoubtedly significant for the study of the formation of this pair of minerals. Author used natural diabasa and marble as starting test materials.The expe- riments were carried out in a cold-seal high-pressure vessel with a gold lining. The experimental results show that the diopside-acmite paragenesis is formed wi- thin the range of 90% diabase and 10% marble to 50% diabase and 50% mar- ble,under the temperature of 500一650 ℃ and the pressure of 500一650℃ bar.,and in a nearly neutral medium of Xco2=0.0104一0.002 within the H20一C02 fluid. Some of the diopside-acmite solid solution produced in our tests has a per- fect crystal form, It is found that in this solid solution, the diopside is always more and the acmite less.This pair of minerals is often associated with garnet, tremolite, vesuvianite, and magnetite, etc. Because of the small ranges of tom- perature, pressure, pH of the medium solution and Xco2 for the coexistence of this pair of minerals, they seidom occur together in metasomatic rocks in nature.
Abstract:Grimaldiite, a hydroxylate of curomium recognized recently in Yunnan Province of China, occurs mainly in the contact zone of an ultrahasic mass. It differs from Guyanese merumite, a complex mixture of varied chrome mine- rals, in that it has single mineral constituent and although it bears similarity to Guyanese grimaldiite in composition and properties, the latter is present as an interarowth of grimaldiite-mcconnellite. Grimaldiite is of the heterogenite type structure belonging to rhombohe dral system with space group R3m, where a0=2.973±0.004A,c0=13.341±0.02A (according to hexagonal system).Chemical analysis yielded, Cr2O3 70.19, H2O+ 12.72, Al2O3 10.23, Fe203 1.44, TiO2l.15, V2O3 0.16, SiO2 0.72, sum 99.82%， corresnondine to (Cr0.800AL0.167Fe0.013Ti0.012V0.002)0.994OOH. Its refractive index is higher than 1.96, density 3.80, (meas.)3.926 g/cm3 (calc.).
Abstract:Conditions have been studied for the formaton and extraction of a complex of copper with 3，5-diBr-PADAT in the presence of peroxide at pH 3 .8. ε570= 8.6× 10. HTTA-bnzene extract the complex by 98-102%.Calibration curve for copper was linear withina a range 0.5～10ug/25m1.
Abstract:A colotimetric method for the determination of nanogram amount of mercury based on the formation of the red complex with Thio-Michlers ketone is described. The pH of the solution is adjusted to 4～6 with a acetate buffer. The calibration curve for mercury was linear withina range of 0.515 ug/25m1(ε550nm = 1.5 × 105).
Abstract:The Sample was decomposed with Na2C03+KCIO3+ZnO. After extraction with water, an aliquot portion of the solution was taken for direct colori- metric determination, which was based on the decolorisation of the purple com- plex formed by arsenazo III with zirconium.
Abstract:A simple method of atomic absorption apectrophotometric determination of chromium in ores was tested. The interference from iron and magnesium ions is solution was eliminated by adding suitable amonat of the restrainer solution(Na2SO4). This method must be free from chloride substance. The samples were sintered with sodium peroxide，and the leaching liquor was neutralized by adding 18 N sulfuric acid. The detection limit is 0.05 /ug/ml.
Abstract:This work concerns analyses performed by emission spectrometry employing ICP source for sample excitation. A domestic plasma generator was used and the porch was positioned horizontally to reduce background caused by intense plasma radiation and to increase the residence time of excited atoms in the source path, so that the limits of determination of 16 rare earth elements including scandium were nearly tenfold lower than that of conventional vertically positioned to3cch. The detection limits of different elements were in the range of O.OOx- O.Ox ug/ml. and would be in the range of O.OOOOx-O.OOx ug/ml. if desolvatiou system was used. The RSd are usually around 4%.
Abstract:This paper descibes the determination of Rb and Sr in silicate samples by energy-dispersive X-Ray fluorescence method, in which the internal-standard method was used. The C.V. for 17 determinations were 4.6 and 3.4% for 0.1% Rb and Sr, respectively. The sensitivity of this method were 0.0003% for Sr and 0.001% for Rb.
